mirror of
https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115951 91177308-0d34-0410-b5e6-96231b3b80d8
1053 lines
38 KiB
C++
1053 lines
38 KiB
C++
//===---------- SplitKit.cpp - Toolkit for splitting live ranges ----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the SplitAnalysis class as well as mutator functions for
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// live range splitting.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "splitter"
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#include "SplitKit.h"
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#include "VirtRegMap.h"
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#include "llvm/CodeGen/CalcSpillWeights.h"
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#include "llvm/CodeGen/LiveIntervalAnalysis.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineLoopInfo.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Target/TargetMachine.h"
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using namespace llvm;
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static cl::opt<bool>
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AllowSplit("spiller-splits-edges",
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cl::desc("Allow critical edge splitting during spilling"));
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//===----------------------------------------------------------------------===//
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// Split Analysis
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//===----------------------------------------------------------------------===//
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SplitAnalysis::SplitAnalysis(const MachineFunction &mf,
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const LiveIntervals &lis,
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const MachineLoopInfo &mli)
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: mf_(mf),
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lis_(lis),
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loops_(mli),
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tii_(*mf.getTarget().getInstrInfo()),
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curli_(0) {}
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void SplitAnalysis::clear() {
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usingInstrs_.clear();
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usingBlocks_.clear();
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usingLoops_.clear();
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curli_ = 0;
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}
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bool SplitAnalysis::canAnalyzeBranch(const MachineBasicBlock *MBB) {
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MachineBasicBlock *T, *F;
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SmallVector<MachineOperand, 4> Cond;
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return !tii_.AnalyzeBranch(const_cast<MachineBasicBlock&>(*MBB), T, F, Cond);
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}
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/// analyzeUses - Count instructions, basic blocks, and loops using curli.
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void SplitAnalysis::analyzeUses() {
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const MachineRegisterInfo &MRI = mf_.getRegInfo();
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for (MachineRegisterInfo::reg_iterator I = MRI.reg_begin(curli_->reg);
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MachineInstr *MI = I.skipInstruction();) {
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if (MI->isDebugValue() || !usingInstrs_.insert(MI))
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continue;
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MachineBasicBlock *MBB = MI->getParent();
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if (usingBlocks_[MBB]++)
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continue;
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for (MachineLoop *Loop = loops_.getLoopFor(MBB); Loop;
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Loop = Loop->getParentLoop())
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usingLoops_[Loop]++;
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}
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DEBUG(dbgs() << " counted "
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<< usingInstrs_.size() << " instrs, "
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<< usingBlocks_.size() << " blocks, "
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<< usingLoops_.size() << " loops.\n");
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}
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// Get three sets of basic blocks surrounding a loop: Blocks inside the loop,
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// predecessor blocks, and exit blocks.
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void SplitAnalysis::getLoopBlocks(const MachineLoop *Loop, LoopBlocks &Blocks) {
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Blocks.clear();
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// Blocks in the loop.
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Blocks.Loop.insert(Loop->block_begin(), Loop->block_end());
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// Predecessor blocks.
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const MachineBasicBlock *Header = Loop->getHeader();
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for (MachineBasicBlock::const_pred_iterator I = Header->pred_begin(),
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E = Header->pred_end(); I != E; ++I)
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if (!Blocks.Loop.count(*I))
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Blocks.Preds.insert(*I);
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// Exit blocks.
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for (MachineLoop::block_iterator I = Loop->block_begin(),
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E = Loop->block_end(); I != E; ++I) {
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const MachineBasicBlock *MBB = *I;
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for (MachineBasicBlock::const_succ_iterator SI = MBB->succ_begin(),
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SE = MBB->succ_end(); SI != SE; ++SI)
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if (!Blocks.Loop.count(*SI))
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Blocks.Exits.insert(*SI);
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}
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}
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/// analyzeLoopPeripheralUse - Return an enum describing how curli_ is used in
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/// and around the Loop.
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SplitAnalysis::LoopPeripheralUse SplitAnalysis::
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analyzeLoopPeripheralUse(const SplitAnalysis::LoopBlocks &Blocks) {
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LoopPeripheralUse use = ContainedInLoop;
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for (BlockCountMap::iterator I = usingBlocks_.begin(), E = usingBlocks_.end();
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I != E; ++I) {
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const MachineBasicBlock *MBB = I->first;
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// Is this a peripheral block?
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if (use < MultiPeripheral &&
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(Blocks.Preds.count(MBB) || Blocks.Exits.count(MBB))) {
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if (I->second > 1) use = MultiPeripheral;
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else use = SinglePeripheral;
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continue;
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}
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// Is it a loop block?
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if (Blocks.Loop.count(MBB))
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continue;
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// It must be an unrelated block.
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return OutsideLoop;
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}
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return use;
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}
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/// getCriticalExits - It may be necessary to partially break critical edges
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/// leaving the loop if an exit block has phi uses of curli. Collect the exit
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/// blocks that need special treatment into CriticalExits.
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void SplitAnalysis::getCriticalExits(const SplitAnalysis::LoopBlocks &Blocks,
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BlockPtrSet &CriticalExits) {
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CriticalExits.clear();
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// A critical exit block contains a phi def of curli, and has a predecessor
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// that is not in the loop nor a loop predecessor.
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// For such an exit block, the edges carrying the new variable must be moved
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// to a new pre-exit block.
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for (BlockPtrSet::iterator I = Blocks.Exits.begin(), E = Blocks.Exits.end();
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I != E; ++I) {
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const MachineBasicBlock *Succ = *I;
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SlotIndex SuccIdx = lis_.getMBBStartIdx(Succ);
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VNInfo *SuccVNI = curli_->getVNInfoAt(SuccIdx);
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// This exit may not have curli live in at all. No need to split.
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if (!SuccVNI)
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continue;
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// If this is not a PHI def, it is either using a value from before the
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// loop, or a value defined inside the loop. Both are safe.
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if (!SuccVNI->isPHIDef() || SuccVNI->def.getBaseIndex() != SuccIdx)
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continue;
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// This exit block does have a PHI. Does it also have a predecessor that is
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// not a loop block or loop predecessor?
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for (MachineBasicBlock::const_pred_iterator PI = Succ->pred_begin(),
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PE = Succ->pred_end(); PI != PE; ++PI) {
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const MachineBasicBlock *Pred = *PI;
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if (Blocks.Loop.count(Pred) || Blocks.Preds.count(Pred))
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continue;
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// This is a critical exit block, and we need to split the exit edge.
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CriticalExits.insert(Succ);
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break;
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}
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}
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}
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/// canSplitCriticalExits - Return true if it is possible to insert new exit
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/// blocks before the blocks in CriticalExits.
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bool
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SplitAnalysis::canSplitCriticalExits(const SplitAnalysis::LoopBlocks &Blocks,
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BlockPtrSet &CriticalExits) {
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// If we don't allow critical edge splitting, require no critical exits.
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if (!AllowSplit)
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return CriticalExits.empty();
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for (BlockPtrSet::iterator I = CriticalExits.begin(), E = CriticalExits.end();
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I != E; ++I) {
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const MachineBasicBlock *Succ = *I;
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// We want to insert a new pre-exit MBB before Succ, and change all the
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// in-loop blocks to branch to the pre-exit instead of Succ.
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// Check that all the in-loop predecessors can be changed.
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for (MachineBasicBlock::const_pred_iterator PI = Succ->pred_begin(),
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PE = Succ->pred_end(); PI != PE; ++PI) {
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const MachineBasicBlock *Pred = *PI;
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// The external predecessors won't be altered.
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if (!Blocks.Loop.count(Pred) && !Blocks.Preds.count(Pred))
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continue;
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if (!canAnalyzeBranch(Pred))
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return false;
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}
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// If Succ's layout predecessor falls through, that too must be analyzable.
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// We need to insert the pre-exit block in the gap.
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MachineFunction::const_iterator MFI = Succ;
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if (MFI == mf_.begin())
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continue;
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if (!canAnalyzeBranch(--MFI))
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return false;
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}
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// No problems found.
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return true;
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}
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void SplitAnalysis::analyze(const LiveInterval *li) {
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clear();
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curli_ = li;
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analyzeUses();
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}
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const MachineLoop *SplitAnalysis::getBestSplitLoop() {
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assert(curli_ && "Call analyze() before getBestSplitLoop");
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if (usingLoops_.empty())
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return 0;
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LoopPtrSet Loops, SecondLoops;
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LoopBlocks Blocks;
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BlockPtrSet CriticalExits;
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// Find first-class and second class candidate loops.
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// We prefer to split around loops where curli is used outside the periphery.
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for (LoopCountMap::const_iterator I = usingLoops_.begin(),
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E = usingLoops_.end(); I != E; ++I) {
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const MachineLoop *Loop = I->first;
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getLoopBlocks(Loop, Blocks);
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LoopPtrSet *LPS = 0;
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switch(analyzeLoopPeripheralUse(Blocks)) {
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case OutsideLoop:
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LPS = &Loops;
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break;
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case MultiPeripheral:
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LPS = &SecondLoops;
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break;
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case ContainedInLoop:
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DEBUG(dbgs() << " contained in " << *Loop);
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continue;
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case SinglePeripheral:
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DEBUG(dbgs() << " single peripheral use in " << *Loop);
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continue;
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}
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// Will it be possible to split around this loop?
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getCriticalExits(Blocks, CriticalExits);
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DEBUG(dbgs() << " " << CriticalExits.size() << " critical exits from "
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<< *Loop);
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if (!canSplitCriticalExits(Blocks, CriticalExits))
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continue;
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// This is a possible split.
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assert(LPS);
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LPS->insert(Loop);
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}
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DEBUG(dbgs() << " getBestSplitLoop found " << Loops.size() << " + "
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<< SecondLoops.size() << " candidate loops.\n");
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// If there are no first class loops available, look at second class loops.
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if (Loops.empty())
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Loops = SecondLoops;
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if (Loops.empty())
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return 0;
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// Pick the earliest loop.
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// FIXME: Are there other heuristics to consider?
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const MachineLoop *Best = 0;
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SlotIndex BestIdx;
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for (LoopPtrSet::const_iterator I = Loops.begin(), E = Loops.end(); I != E;
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++I) {
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SlotIndex Idx = lis_.getMBBStartIdx((*I)->getHeader());
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if (!Best || Idx < BestIdx)
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Best = *I, BestIdx = Idx;
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}
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DEBUG(dbgs() << " getBestSplitLoop found " << *Best);
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return Best;
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}
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/// getMultiUseBlocks - if curli has more than one use in a basic block, it
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/// may be an advantage to split curli for the duration of the block.
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bool SplitAnalysis::getMultiUseBlocks(BlockPtrSet &Blocks) {
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// If curli is local to one block, there is no point to splitting it.
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if (usingBlocks_.size() <= 1)
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return false;
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// Add blocks with multiple uses.
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for (BlockCountMap::iterator I = usingBlocks_.begin(), E = usingBlocks_.end();
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I != E; ++I)
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switch (I->second) {
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case 0:
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case 1:
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continue;
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case 2: {
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// It doesn't pay to split a 2-instr block if it redefines curli.
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VNInfo *VN1 = curli_->getVNInfoAt(lis_.getMBBStartIdx(I->first));
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VNInfo *VN2 =
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curli_->getVNInfoAt(lis_.getMBBEndIdx(I->first).getPrevIndex());
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// live-in and live-out with a different value.
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if (VN1 && VN2 && VN1 != VN2)
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continue;
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} // Fall through.
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default:
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Blocks.insert(I->first);
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}
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return !Blocks.empty();
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}
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//===----------------------------------------------------------------------===//
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// LiveIntervalMap
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//===----------------------------------------------------------------------===//
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// Work around the fact that the std::pair constructors are broken for pointer
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// pairs in some implementations. makeVV(x, 0) works.
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static inline std::pair<const VNInfo*, VNInfo*>
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makeVV(const VNInfo *a, VNInfo *b) {
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return std::make_pair(a, b);
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}
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void LiveIntervalMap::reset(LiveInterval *li) {
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li_ = li;
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valueMap_.clear();
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}
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bool LiveIntervalMap::isComplexMapped(const VNInfo *ParentVNI) const {
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ValueMap::const_iterator i = valueMap_.find(ParentVNI);
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return i != valueMap_.end() && i->second == 0;
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}
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// defValue - Introduce a li_ def for ParentVNI that could be later than
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// ParentVNI->def.
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VNInfo *LiveIntervalMap::defValue(const VNInfo *ParentVNI, SlotIndex Idx) {
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assert(li_ && "call reset first");
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assert(ParentVNI && "Mapping NULL value");
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assert(Idx.isValid() && "Invalid SlotIndex");
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assert(parentli_.getVNInfoAt(Idx) == ParentVNI && "Bad ParentVNI");
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// Create a new value.
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VNInfo *VNI = li_->getNextValue(Idx, 0, lis_.getVNInfoAllocator());
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// Use insert for lookup, so we can add missing values with a second lookup.
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std::pair<ValueMap::iterator,bool> InsP =
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valueMap_.insert(makeVV(ParentVNI, Idx == ParentVNI->def ? VNI : 0));
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// This is now a complex def. Mark with a NULL in valueMap.
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if (!InsP.second)
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InsP.first->second = 0;
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return VNI;
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}
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// mapValue - Find the mapped value for ParentVNI at Idx.
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// Potentially create phi-def values.
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VNInfo *LiveIntervalMap::mapValue(const VNInfo *ParentVNI, SlotIndex Idx,
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bool *simple) {
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assert(li_ && "call reset first");
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assert(ParentVNI && "Mapping NULL value");
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assert(Idx.isValid() && "Invalid SlotIndex");
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assert(parentli_.getVNInfoAt(Idx) == ParentVNI && "Bad ParentVNI");
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// Use insert for lookup, so we can add missing values with a second lookup.
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std::pair<ValueMap::iterator,bool> InsP =
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valueMap_.insert(makeVV(ParentVNI, 0));
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// This was an unknown value. Create a simple mapping.
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if (InsP.second) {
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if (simple) *simple = true;
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return InsP.first->second = li_->createValueCopy(ParentVNI,
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lis_.getVNInfoAllocator());
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}
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// This was a simple mapped value.
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if (InsP.first->second) {
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if (simple) *simple = true;
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return InsP.first->second;
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}
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// This is a complex mapped value. There may be multiple defs, and we may need
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// to create phi-defs.
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if (simple) *simple = false;
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MachineBasicBlock *IdxMBB = lis_.getMBBFromIndex(Idx);
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assert(IdxMBB && "No MBB at Idx");
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// Is there a def in the same MBB we can extend?
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if (VNInfo *VNI = extendTo(IdxMBB, Idx))
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return VNI;
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// Now for the fun part. We know that ParentVNI potentially has multiple defs,
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// and we may need to create even more phi-defs to preserve VNInfo SSA form.
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// Perform a depth-first search for predecessor blocks where we know the
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// dominating VNInfo. Insert phi-def VNInfos along the path back to IdxMBB.
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// Track MBBs where we have created or learned the dominating value.
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// This may change during the DFS as we create new phi-defs.
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typedef DenseMap<MachineBasicBlock*, VNInfo*> MBBValueMap;
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MBBValueMap DomValue;
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typedef SplitAnalysis::BlockPtrSet BlockPtrSet;
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BlockPtrSet Visited;
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// Iterate over IdxMBB predecessors in a depth-first order.
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// Skip begin() since that is always IdxMBB.
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for (idf_ext_iterator<MachineBasicBlock*, BlockPtrSet>
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IDFI = llvm::next(idf_ext_begin(IdxMBB, Visited)),
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IDFE = idf_ext_end(IdxMBB, Visited); IDFI != IDFE;) {
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MachineBasicBlock *MBB = *IDFI;
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SlotIndex End = lis_.getMBBEndIdx(MBB).getPrevSlot();
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// We are operating on the restricted CFG where ParentVNI is live.
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if (parentli_.getVNInfoAt(End) != ParentVNI) {
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IDFI.skipChildren();
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continue;
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}
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// Do we have a dominating value in this block?
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VNInfo *VNI = extendTo(MBB, End);
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if (!VNI) {
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++IDFI;
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continue;
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}
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// Yes, VNI dominates MBB. Make sure we visit MBB again from other paths.
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Visited.erase(MBB);
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// Track the path back to IdxMBB, creating phi-defs
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// as needed along the way.
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for (unsigned PI = IDFI.getPathLength()-1; PI != 0; --PI) {
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// Start from MBB's immediate successor. End at IdxMBB.
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MachineBasicBlock *Succ = IDFI.getPath(PI-1);
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std::pair<MBBValueMap::iterator, bool> InsP =
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DomValue.insert(MBBValueMap::value_type(Succ, VNI));
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// This is the first time we backtrack to Succ.
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if (InsP.second)
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continue;
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// We reached Succ again with the same VNI. Nothing is going to change.
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VNInfo *OVNI = InsP.first->second;
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if (OVNI == VNI)
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break;
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// Succ already has a phi-def. No need to continue.
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SlotIndex Start = lis_.getMBBStartIdx(Succ);
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if (OVNI->def == Start)
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break;
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// We have a collision between the old and new VNI at Succ. That means
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// neither dominates and we need a new phi-def.
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VNI = li_->getNextValue(Start, 0, lis_.getVNInfoAllocator());
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VNI->setIsPHIDef(true);
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InsP.first->second = VNI;
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// Replace OVNI with VNI in the remaining path.
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for (; PI > 1 ; --PI) {
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MBBValueMap::iterator I = DomValue.find(IDFI.getPath(PI-2));
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if (I == DomValue.end() || I->second != OVNI)
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break;
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I->second = VNI;
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}
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}
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// No need to search the children, we found a dominating value.
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IDFI.skipChildren();
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}
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// The search should at least find a dominating value for IdxMBB.
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assert(!DomValue.empty() && "Couldn't find a reaching definition");
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// Since we went through the trouble of a full DFS visiting all reaching defs,
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// the values in DomValue are now accurate. No more phi-defs are needed for
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// these blocks, so we can color the live ranges.
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// This makes the next mapValue call much faster.
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VNInfo *IdxVNI = 0;
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for (MBBValueMap::iterator I = DomValue.begin(), E = DomValue.end(); I != E;
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++I) {
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MachineBasicBlock *MBB = I->first;
|
|
VNInfo *VNI = I->second;
|
|
SlotIndex Start = lis_.getMBBStartIdx(MBB);
|
|
if (MBB == IdxMBB) {
|
|
// Don't add full liveness to IdxMBB, stop at Idx.
|
|
if (Start != Idx)
|
|
li_->addRange(LiveRange(Start, Idx.getNextSlot(), VNI));
|
|
// The caller had better add some liveness to IdxVNI, or it leaks.
|
|
IdxVNI = VNI;
|
|
} else
|
|
li_->addRange(LiveRange(Start, lis_.getMBBEndIdx(MBB), VNI));
|
|
}
|
|
|
|
assert(IdxVNI && "Didn't find value for Idx");
|
|
return IdxVNI;
|
|
}
|
|
|
|
// extendTo - Find the last li_ value defined in MBB at or before Idx. The
|
|
// parentli_ is assumed to be live at Idx. Extend the live range to Idx.
|
|
// Return the found VNInfo, or NULL.
|
|
VNInfo *LiveIntervalMap::extendTo(MachineBasicBlock *MBB, SlotIndex Idx) {
|
|
assert(li_ && "call reset first");
|
|
LiveInterval::iterator I = std::upper_bound(li_->begin(), li_->end(), Idx);
|
|
if (I == li_->begin())
|
|
return 0;
|
|
--I;
|
|
if (I->end <= lis_.getMBBStartIdx(MBB))
|
|
return 0;
|
|
if (I->end <= Idx)
|
|
I->end = Idx.getNextSlot();
|
|
return I->valno;
|
|
}
|
|
|
|
// addSimpleRange - Add a simple range from parentli_ to li_.
|
|
// ParentVNI must be live in the [Start;End) interval.
|
|
void LiveIntervalMap::addSimpleRange(SlotIndex Start, SlotIndex End,
|
|
const VNInfo *ParentVNI) {
|
|
assert(li_ && "call reset first");
|
|
bool simple;
|
|
VNInfo *VNI = mapValue(ParentVNI, Start, &simple);
|
|
// A simple mapping is easy.
|
|
if (simple) {
|
|
li_->addRange(LiveRange(Start, End, VNI));
|
|
return;
|
|
}
|
|
|
|
// ParentVNI is a complex value. We must map per MBB.
|
|
MachineFunction::iterator MBB = lis_.getMBBFromIndex(Start);
|
|
MachineFunction::iterator MBBE = lis_.getMBBFromIndex(End.getPrevSlot());
|
|
|
|
if (MBB == MBBE) {
|
|
li_->addRange(LiveRange(Start, End, VNI));
|
|
return;
|
|
}
|
|
|
|
// First block.
|
|
li_->addRange(LiveRange(Start, lis_.getMBBEndIdx(MBB), VNI));
|
|
|
|
// Run sequence of full blocks.
|
|
for (++MBB; MBB != MBBE; ++MBB) {
|
|
Start = lis_.getMBBStartIdx(MBB);
|
|
li_->addRange(LiveRange(Start, lis_.getMBBEndIdx(MBB),
|
|
mapValue(ParentVNI, Start)));
|
|
}
|
|
|
|
// Final block.
|
|
Start = lis_.getMBBStartIdx(MBB);
|
|
if (Start != End)
|
|
li_->addRange(LiveRange(Start, End, mapValue(ParentVNI, Start)));
|
|
}
|
|
|
|
/// addRange - Add live ranges to li_ where [Start;End) intersects parentli_.
|
|
/// All needed values whose def is not inside [Start;End) must be defined
|
|
/// beforehand so mapValue will work.
|
|
void LiveIntervalMap::addRange(SlotIndex Start, SlotIndex End) {
|
|
assert(li_ && "call reset first");
|
|
LiveInterval::const_iterator B = parentli_.begin(), E = parentli_.end();
|
|
LiveInterval::const_iterator I = std::lower_bound(B, E, Start);
|
|
|
|
// Check if --I begins before Start and overlaps.
|
|
if (I != B) {
|
|
--I;
|
|
if (I->end > Start)
|
|
addSimpleRange(Start, std::min(End, I->end), I->valno);
|
|
++I;
|
|
}
|
|
|
|
// The remaining ranges begin after Start.
|
|
for (;I != E && I->start < End; ++I)
|
|
addSimpleRange(I->start, std::min(End, I->end), I->valno);
|
|
}
|
|
|
|
VNInfo *LiveIntervalMap::defByCopyFrom(unsigned Reg,
|
|
const VNInfo *ParentVNI,
|
|
MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator I) {
|
|
const TargetInstrDesc &TID = MBB.getParent()->getTarget().getInstrInfo()->
|
|
get(TargetOpcode::COPY);
|
|
MachineInstr *MI = BuildMI(MBB, I, DebugLoc(), TID, li_->reg).addReg(Reg);
|
|
SlotIndex DefIdx = lis_.InsertMachineInstrInMaps(MI).getDefIndex();
|
|
VNInfo *VNI = defValue(ParentVNI, DefIdx);
|
|
VNI->setCopy(MI);
|
|
li_->addRange(LiveRange(DefIdx, DefIdx.getNextSlot(), VNI));
|
|
return VNI;
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Split Editor
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// Create a new SplitEditor for editing the LiveInterval analyzed by SA.
|
|
SplitEditor::SplitEditor(SplitAnalysis &sa, LiveIntervals &lis, VirtRegMap &vrm,
|
|
SmallVectorImpl<LiveInterval*> &intervals)
|
|
: sa_(sa), lis_(lis), vrm_(vrm),
|
|
mri_(vrm.getMachineFunction().getRegInfo()),
|
|
tii_(*vrm.getMachineFunction().getTarget().getInstrInfo()),
|
|
curli_(sa_.getCurLI()),
|
|
dupli_(lis_, *curli_),
|
|
openli_(lis_, *curli_),
|
|
intervals_(intervals),
|
|
firstInterval(intervals_.size())
|
|
{
|
|
assert(curli_ && "SplitEditor created from empty SplitAnalysis");
|
|
|
|
// Make sure curli_ is assigned a stack slot, so all our intervals get the
|
|
// same slot as curli_.
|
|
if (vrm_.getStackSlot(curli_->reg) == VirtRegMap::NO_STACK_SLOT)
|
|
vrm_.assignVirt2StackSlot(curli_->reg);
|
|
|
|
}
|
|
|
|
LiveInterval *SplitEditor::createInterval() {
|
|
unsigned Reg = mri_.createVirtualRegister(mri_.getRegClass(curli_->reg));
|
|
LiveInterval &Intv = lis_.getOrCreateInterval(Reg);
|
|
vrm_.grow();
|
|
vrm_.assignVirt2StackSlot(Reg, vrm_.getStackSlot(curli_->reg));
|
|
return &Intv;
|
|
}
|
|
|
|
bool SplitEditor::intervalsLiveAt(SlotIndex Idx) const {
|
|
for (int i = firstInterval, e = intervals_.size(); i != e; ++i)
|
|
if (intervals_[i]->liveAt(Idx))
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
/// Create a new virtual register and live interval.
|
|
void SplitEditor::openIntv() {
|
|
assert(!openli_.getLI() && "Previous LI not closed before openIntv");
|
|
|
|
if (!dupli_.getLI())
|
|
dupli_.reset(createInterval());
|
|
|
|
openli_.reset(createInterval());
|
|
intervals_.push_back(openli_.getLI());
|
|
}
|
|
|
|
/// enterIntvBefore - Enter openli before the instruction at Idx. If curli is
|
|
/// not live before Idx, a COPY is not inserted.
|
|
void SplitEditor::enterIntvBefore(SlotIndex Idx) {
|
|
assert(openli_.getLI() && "openIntv not called before enterIntvBefore");
|
|
DEBUG(dbgs() << " enterIntvBefore " << Idx);
|
|
VNInfo *ParentVNI = curli_->getVNInfoAt(Idx.getUseIndex());
|
|
if (!ParentVNI) {
|
|
DEBUG(dbgs() << ": not live\n");
|
|
return;
|
|
}
|
|
DEBUG(dbgs() << ": valno " << ParentVNI->id);
|
|
truncatedValues.insert(ParentVNI);
|
|
MachineInstr *MI = lis_.getInstructionFromIndex(Idx);
|
|
assert(MI && "enterIntvBefore called with invalid index");
|
|
VNInfo *VNI = openli_.defByCopyFrom(curli_->reg, ParentVNI,
|
|
*MI->getParent(), MI);
|
|
openli_.getLI()->addRange(LiveRange(VNI->def, Idx.getDefIndex(), VNI));
|
|
DEBUG(dbgs() << ": " << *openli_.getLI() << '\n');
|
|
}
|
|
|
|
/// enterIntvAtEnd - Enter openli at the end of MBB.
|
|
void SplitEditor::enterIntvAtEnd(MachineBasicBlock &MBB) {
|
|
assert(openli_.getLI() && "openIntv not called before enterIntvAtEnd");
|
|
SlotIndex End = lis_.getMBBEndIdx(&MBB);
|
|
DEBUG(dbgs() << " enterIntvAtEnd BB#" << MBB.getNumber() << ", " << End);
|
|
VNInfo *ParentVNI = curli_->getVNInfoAt(End.getPrevSlot());
|
|
if (!ParentVNI) {
|
|
DEBUG(dbgs() << ": not live\n");
|
|
return;
|
|
}
|
|
DEBUG(dbgs() << ": valno " << ParentVNI->id);
|
|
truncatedValues.insert(ParentVNI);
|
|
VNInfo *VNI = openli_.defByCopyFrom(curli_->reg, ParentVNI,
|
|
MBB, MBB.getFirstTerminator());
|
|
// Make sure openli is live out of MBB.
|
|
openli_.getLI()->addRange(LiveRange(VNI->def, End, VNI));
|
|
DEBUG(dbgs() << ": " << *openli_.getLI() << '\n');
|
|
}
|
|
|
|
/// useIntv - indicate that all instructions in MBB should use openli.
|
|
void SplitEditor::useIntv(const MachineBasicBlock &MBB) {
|
|
useIntv(lis_.getMBBStartIdx(&MBB), lis_.getMBBEndIdx(&MBB));
|
|
}
|
|
|
|
void SplitEditor::useIntv(SlotIndex Start, SlotIndex End) {
|
|
assert(openli_.getLI() && "openIntv not called before useIntv");
|
|
openli_.addRange(Start, End);
|
|
DEBUG(dbgs() << " use [" << Start << ';' << End << "): "
|
|
<< *openli_.getLI() << '\n');
|
|
}
|
|
|
|
/// leaveIntvAfter - Leave openli after the instruction at Idx.
|
|
void SplitEditor::leaveIntvAfter(SlotIndex Idx) {
|
|
assert(openli_.getLI() && "openIntv not called before leaveIntvAfter");
|
|
DEBUG(dbgs() << " leaveIntvAfter " << Idx);
|
|
|
|
// The interval must be live beyond the instruction at Idx.
|
|
VNInfo *ParentVNI = curli_->getVNInfoAt(Idx.getBoundaryIndex());
|
|
if (!ParentVNI) {
|
|
DEBUG(dbgs() << ": not live\n");
|
|
return;
|
|
}
|
|
DEBUG(dbgs() << ": valno " << ParentVNI->id);
|
|
|
|
MachineBasicBlock::iterator MII = lis_.getInstructionFromIndex(Idx);
|
|
MachineBasicBlock *MBB = MII->getParent();
|
|
VNInfo *VNI = dupli_.defByCopyFrom(openli_.getLI()->reg, ParentVNI, *MBB,
|
|
llvm::next(MII));
|
|
|
|
// Finally we must make sure that openli is properly extended from Idx to the
|
|
// new copy.
|
|
openli_.addSimpleRange(Idx.getBoundaryIndex(), VNI->def, ParentVNI);
|
|
DEBUG(dbgs() << ": " << *openli_.getLI() << '\n');
|
|
}
|
|
|
|
/// leaveIntvAtTop - Leave the interval at the top of MBB.
|
|
/// Currently, only one value can leave the interval.
|
|
void SplitEditor::leaveIntvAtTop(MachineBasicBlock &MBB) {
|
|
assert(openli_.getLI() && "openIntv not called before leaveIntvAtTop");
|
|
SlotIndex Start = lis_.getMBBStartIdx(&MBB);
|
|
DEBUG(dbgs() << " leaveIntvAtTop BB#" << MBB.getNumber() << ", " << Start);
|
|
|
|
VNInfo *ParentVNI = curli_->getVNInfoAt(Start);
|
|
if (!ParentVNI) {
|
|
DEBUG(dbgs() << ": not live\n");
|
|
return;
|
|
}
|
|
|
|
// We are going to insert a back copy, so we must have a dupli_.
|
|
VNInfo *VNI = dupli_.defByCopyFrom(openli_.getLI()->reg, ParentVNI,
|
|
MBB, MBB.begin());
|
|
|
|
// Finally we must make sure that openli is properly extended from Start to
|
|
// the new copy.
|
|
openli_.addSimpleRange(Start, VNI->def, ParentVNI);
|
|
DEBUG(dbgs() << ": " << *openli_.getLI() << '\n');
|
|
}
|
|
|
|
/// closeIntv - Indicate that we are done editing the currently open
|
|
/// LiveInterval, and ranges can be trimmed.
|
|
void SplitEditor::closeIntv() {
|
|
assert(openli_.getLI() && "openIntv not called before closeIntv");
|
|
|
|
DEBUG(dbgs() << " closeIntv cleaning up\n");
|
|
DEBUG(dbgs() << " open " << *openli_.getLI() << '\n');
|
|
openli_.reset(0);
|
|
}
|
|
|
|
void
|
|
SplitEditor::addTruncSimpleRange(SlotIndex Start, SlotIndex End, VNInfo *VNI) {
|
|
// Build vector of iterator pairs from the intervals.
|
|
typedef std::pair<LiveInterval::const_iterator,
|
|
LiveInterval::const_iterator> IIPair;
|
|
SmallVector<IIPair, 8> Iters;
|
|
for (int i = firstInterval, e = intervals_.size(); i != e; ++i) {
|
|
LiveInterval::const_iterator I = intervals_[i]->find(Start);
|
|
LiveInterval::const_iterator E = intervals_[i]->end();
|
|
if (I != E)
|
|
Iters.push_back(std::make_pair(I, E));
|
|
}
|
|
|
|
SlotIndex sidx = Start;
|
|
// Break [Start;End) into segments that don't overlap any intervals.
|
|
for (;;) {
|
|
SlotIndex next = sidx, eidx = End;
|
|
// Find overlapping intervals.
|
|
for (unsigned i = 0; i != Iters.size() && sidx < eidx; ++i) {
|
|
LiveInterval::const_iterator I = Iters[i].first;
|
|
// Interval I is overlapping [sidx;eidx). Trim sidx.
|
|
if (I->start <= sidx) {
|
|
sidx = I->end;
|
|
// Move to the next run, remove iters when all are consumed.
|
|
I = ++Iters[i].first;
|
|
if (I == Iters[i].second) {
|
|
Iters.erase(Iters.begin() + i);
|
|
--i;
|
|
continue;
|
|
}
|
|
}
|
|
// Trim eidx too if needed.
|
|
if (I->start >= eidx)
|
|
continue;
|
|
eidx = I->start;
|
|
next = I->end;
|
|
}
|
|
// Now, [sidx;eidx) doesn't overlap anything in intervals_.
|
|
if (sidx < eidx)
|
|
dupli_.addSimpleRange(sidx, eidx, VNI);
|
|
// If the interval end was truncated, we can try again from next.
|
|
if (next <= sidx)
|
|
break;
|
|
sidx = next;
|
|
}
|
|
}
|
|
|
|
/// rewrite - after all the new live ranges have been created, rewrite
|
|
/// instructions using curli to use the new intervals.
|
|
void SplitEditor::rewrite() {
|
|
assert(!openli_.getLI() && "Previous LI not closed before rewrite");
|
|
assert(dupli_.getLI() && "No dupli for rewrite. Noop spilt?");
|
|
|
|
// First we need to fill in the live ranges in dupli.
|
|
// If values were redefined, we need a full recoloring with SSA update.
|
|
// If values were truncated, we only need to truncate the ranges.
|
|
// If values were partially rematted, we should shrink to uses.
|
|
// If values were fully rematted, they should be omitted.
|
|
// FIXME: If a single value is redefined, just move the def and truncate.
|
|
|
|
// Values that are fully contained in the split intervals.
|
|
SmallPtrSet<const VNInfo*, 8> deadValues;
|
|
|
|
// Map all curli values that should have live defs in dupli.
|
|
for (LiveInterval::const_vni_iterator I = curli_->vni_begin(),
|
|
E = curli_->vni_end(); I != E; ++I) {
|
|
const VNInfo *VNI = *I;
|
|
// Original def is contained in the split intervals.
|
|
if (intervalsLiveAt(VNI->def)) {
|
|
// Did this value escape?
|
|
if (dupli_.isMapped(VNI))
|
|
truncatedValues.insert(VNI);
|
|
else
|
|
deadValues.insert(VNI);
|
|
continue;
|
|
}
|
|
// Add minimal live range at the definition.
|
|
VNInfo *DVNI = dupli_.defValue(VNI, VNI->def);
|
|
dupli_.getLI()->addRange(LiveRange(VNI->def, VNI->def.getNextSlot(), DVNI));
|
|
}
|
|
|
|
// Add all ranges to dupli.
|
|
for (LiveInterval::const_iterator I = curli_->begin(), E = curli_->end();
|
|
I != E; ++I) {
|
|
const LiveRange &LR = *I;
|
|
if (truncatedValues.count(LR.valno)) {
|
|
// recolor after removing intervals_.
|
|
addTruncSimpleRange(LR.start, LR.end, LR.valno);
|
|
} else if (!deadValues.count(LR.valno)) {
|
|
// recolor without truncation.
|
|
dupli_.addSimpleRange(LR.start, LR.end, LR.valno);
|
|
}
|
|
}
|
|
|
|
|
|
const LiveInterval *curli = sa_.getCurLI();
|
|
for (MachineRegisterInfo::reg_iterator RI = mri_.reg_begin(curli->reg),
|
|
RE = mri_.reg_end(); RI != RE;) {
|
|
MachineOperand &MO = RI.getOperand();
|
|
MachineInstr *MI = MO.getParent();
|
|
++RI;
|
|
if (MI->isDebugValue()) {
|
|
DEBUG(dbgs() << "Zapping " << *MI);
|
|
// FIXME: We can do much better with debug values.
|
|
MO.setReg(0);
|
|
continue;
|
|
}
|
|
SlotIndex Idx = lis_.getInstructionIndex(MI);
|
|
Idx = MO.isUse() ? Idx.getUseIndex() : Idx.getDefIndex();
|
|
LiveInterval *LI = dupli_.getLI();
|
|
for (unsigned i = firstInterval, e = intervals_.size(); i != e; ++i) {
|
|
LiveInterval *testli = intervals_[i];
|
|
if (testli->liveAt(Idx)) {
|
|
LI = testli;
|
|
break;
|
|
}
|
|
}
|
|
MO.setReg(LI->reg);
|
|
DEBUG(dbgs() << " rewrite BB#" << MI->getParent()->getNumber() << '\t'
|
|
<< Idx << '\t' << *MI);
|
|
}
|
|
|
|
// dupli_ goes in last, after rewriting.
|
|
if (dupli_.getLI()->empty()) {
|
|
DEBUG(dbgs() << " dupli became empty?\n");
|
|
lis_.removeInterval(dupli_.getLI()->reg);
|
|
dupli_.reset(0);
|
|
} else {
|
|
dupli_.getLI()->RenumberValues(lis_);
|
|
intervals_.push_back(dupli_.getLI());
|
|
}
|
|
|
|
// Calculate spill weight and allocation hints for new intervals.
|
|
VirtRegAuxInfo vrai(vrm_.getMachineFunction(), lis_, sa_.loops_);
|
|
for (unsigned i = firstInterval, e = intervals_.size(); i != e; ++i) {
|
|
LiveInterval &li = *intervals_[i];
|
|
vrai.CalculateRegClass(li.reg);
|
|
vrai.CalculateWeightAndHint(li);
|
|
DEBUG(dbgs() << " new interval " << mri_.getRegClass(li.reg)->getName()
|
|
<< ":" << li << '\n');
|
|
}
|
|
}
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Loop Splitting
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
void SplitEditor::splitAroundLoop(const MachineLoop *Loop) {
|
|
SplitAnalysis::LoopBlocks Blocks;
|
|
sa_.getLoopBlocks(Loop, Blocks);
|
|
|
|
DEBUG({
|
|
dbgs() << " splitAroundLoop";
|
|
for (SplitAnalysis::BlockPtrSet::iterator I = Blocks.Loop.begin(),
|
|
E = Blocks.Loop.end(); I != E; ++I)
|
|
dbgs() << " BB#" << (*I)->getNumber();
|
|
dbgs() << ", preds:";
|
|
for (SplitAnalysis::BlockPtrSet::iterator I = Blocks.Preds.begin(),
|
|
E = Blocks.Preds.end(); I != E; ++I)
|
|
dbgs() << " BB#" << (*I)->getNumber();
|
|
dbgs() << ", exits:";
|
|
for (SplitAnalysis::BlockPtrSet::iterator I = Blocks.Exits.begin(),
|
|
E = Blocks.Exits.end(); I != E; ++I)
|
|
dbgs() << " BB#" << (*I)->getNumber();
|
|
dbgs() << '\n';
|
|
});
|
|
|
|
// Break critical edges as needed.
|
|
SplitAnalysis::BlockPtrSet CriticalExits;
|
|
sa_.getCriticalExits(Blocks, CriticalExits);
|
|
assert(CriticalExits.empty() && "Cannot break critical exits yet");
|
|
|
|
// Create new live interval for the loop.
|
|
openIntv();
|
|
|
|
// Insert copies in the predecessors.
|
|
for (SplitAnalysis::BlockPtrSet::iterator I = Blocks.Preds.begin(),
|
|
E = Blocks.Preds.end(); I != E; ++I) {
|
|
MachineBasicBlock &MBB = const_cast<MachineBasicBlock&>(**I);
|
|
enterIntvAtEnd(MBB);
|
|
}
|
|
|
|
// Switch all loop blocks.
|
|
for (SplitAnalysis::BlockPtrSet::iterator I = Blocks.Loop.begin(),
|
|
E = Blocks.Loop.end(); I != E; ++I)
|
|
useIntv(**I);
|
|
|
|
// Insert back copies in the exit blocks.
|
|
for (SplitAnalysis::BlockPtrSet::iterator I = Blocks.Exits.begin(),
|
|
E = Blocks.Exits.end(); I != E; ++I) {
|
|
MachineBasicBlock &MBB = const_cast<MachineBasicBlock&>(**I);
|
|
leaveIntvAtTop(MBB);
|
|
}
|
|
|
|
// Done.
|
|
closeIntv();
|
|
rewrite();
|
|
}
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Single Block Splitting
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// splitSingleBlocks - Split curli into a separate live interval inside each
|
|
/// basic block in Blocks.
|
|
void SplitEditor::splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks) {
|
|
DEBUG(dbgs() << " splitSingleBlocks for " << Blocks.size() << " blocks.\n");
|
|
// Determine the first and last instruction using curli in each block.
|
|
typedef std::pair<SlotIndex,SlotIndex> IndexPair;
|
|
typedef DenseMap<const MachineBasicBlock*,IndexPair> IndexPairMap;
|
|
IndexPairMap MBBRange;
|
|
for (SplitAnalysis::InstrPtrSet::const_iterator I = sa_.usingInstrs_.begin(),
|
|
E = sa_.usingInstrs_.end(); I != E; ++I) {
|
|
const MachineBasicBlock *MBB = (*I)->getParent();
|
|
if (!Blocks.count(MBB))
|
|
continue;
|
|
SlotIndex Idx = lis_.getInstructionIndex(*I);
|
|
DEBUG(dbgs() << " BB#" << MBB->getNumber() << '\t' << Idx << '\t' << **I);
|
|
IndexPair &IP = MBBRange[MBB];
|
|
if (!IP.first.isValid() || Idx < IP.first)
|
|
IP.first = Idx;
|
|
if (!IP.second.isValid() || Idx > IP.second)
|
|
IP.second = Idx;
|
|
}
|
|
|
|
// Create a new interval for each block.
|
|
for (SplitAnalysis::BlockPtrSet::const_iterator I = Blocks.begin(),
|
|
E = Blocks.end(); I != E; ++I) {
|
|
IndexPair &IP = MBBRange[*I];
|
|
DEBUG(dbgs() << " splitting for BB#" << (*I)->getNumber() << ": ["
|
|
<< IP.first << ';' << IP.second << ")\n");
|
|
assert(IP.first.isValid() && IP.second.isValid());
|
|
|
|
openIntv();
|
|
enterIntvBefore(IP.first);
|
|
useIntv(IP.first.getBaseIndex(), IP.second.getBoundaryIndex());
|
|
leaveIntvAfter(IP.second);
|
|
closeIntv();
|
|
}
|
|
rewrite();
|
|
}
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Sub Block Splitting
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// getBlockForInsideSplit - If curli is contained inside a single basic block,
|
|
/// and it wou pay to subdivide the interval inside that block, return it.
|
|
/// Otherwise return NULL. The returned block can be passed to
|
|
/// SplitEditor::splitInsideBlock.
|
|
const MachineBasicBlock *SplitAnalysis::getBlockForInsideSplit() {
|
|
// The interval must be exclusive to one block.
|
|
if (usingBlocks_.size() != 1)
|
|
return 0;
|
|
// Don't to this for less than 4 instructions. We want to be sure that
|
|
// splitting actually reduces the instruction count per interval.
|
|
if (usingInstrs_.size() < 4)
|
|
return 0;
|
|
return usingBlocks_.begin()->first;
|
|
}
|
|
|
|
/// splitInsideBlock - Split curli into multiple intervals inside MBB.
|
|
void SplitEditor::splitInsideBlock(const MachineBasicBlock *MBB) {
|
|
SmallVector<SlotIndex, 32> Uses;
|
|
Uses.reserve(sa_.usingInstrs_.size());
|
|
for (SplitAnalysis::InstrPtrSet::const_iterator I = sa_.usingInstrs_.begin(),
|
|
E = sa_.usingInstrs_.end(); I != E; ++I)
|
|
if ((*I)->getParent() == MBB)
|
|
Uses.push_back(lis_.getInstructionIndex(*I));
|
|
DEBUG(dbgs() << " splitInsideBlock BB#" << MBB->getNumber() << " for "
|
|
<< Uses.size() << " instructions.\n");
|
|
assert(Uses.size() >= 3 && "Need at least 3 instructions");
|
|
array_pod_sort(Uses.begin(), Uses.end());
|
|
|
|
// Simple algorithm: Find the largest gap between uses as determined by slot
|
|
// indices. Create new intervals for instructions before the gap and after the
|
|
// gap.
|
|
unsigned bestPos = 0;
|
|
int bestGap = 0;
|
|
DEBUG(dbgs() << " dist (" << Uses[0]);
|
|
for (unsigned i = 1, e = Uses.size(); i != e; ++i) {
|
|
int g = Uses[i-1].distance(Uses[i]);
|
|
DEBUG(dbgs() << ") -" << g << "- (" << Uses[i]);
|
|
if (g > bestGap)
|
|
bestPos = i, bestGap = g;
|
|
}
|
|
DEBUG(dbgs() << "), best: -" << bestGap << "-\n");
|
|
|
|
// bestPos points to the first use after the best gap.
|
|
assert(bestPos > 0 && "Invalid gap");
|
|
|
|
// FIXME: Don't create intervals for low densities.
|
|
|
|
// First interval before the gap. Don't create single-instr intervals.
|
|
if (bestPos > 1) {
|
|
openIntv();
|
|
enterIntvBefore(Uses.front());
|
|
useIntv(Uses.front().getBaseIndex(), Uses[bestPos-1].getBoundaryIndex());
|
|
leaveIntvAfter(Uses[bestPos-1]);
|
|
closeIntv();
|
|
}
|
|
|
|
// Second interval after the gap.
|
|
if (bestPos < Uses.size()-1) {
|
|
openIntv();
|
|
enterIntvBefore(Uses[bestPos]);
|
|
useIntv(Uses[bestPos].getBaseIndex(), Uses.back().getBoundaryIndex());
|
|
leaveIntvAfter(Uses.back());
|
|
closeIntv();
|
|
}
|
|
|
|
rewrite();
|
|
}
|